First we plan to determine retrospectively the morphogenesis of the postgastrectomy gastritis greater than metaplasia greater than dysplasia sequence using the adequate-sized biopsies now avialable with new endoscopic instruments. If the threat of postgastrectomy cancer is as great as in parts of Western Europe, a massive screening program might be justified in the United States. Also we wish to better determine the normal distribution of columnar epithelium in the esophagus and its pathology in regurgitant esophagitis with and without Barrett's metaplasia. We hope to document the magnitude of the threat of cancer in this entity and to determine which histologic findings are most predictive of cancer development. Physiologic abnormalities will be correlated with those histologic findings most predictive of cancer in order to better understand pathogenesesis. Finally we wish to determine prospectively if these premalignant conditions can be prevented, arrested or reversed using established surgical techniques and various cytoprotective, antisecretory, and cytorestorative agents that are already in the accepted pharmacopeia for other indications.